If you donate you can also choose which feature should be implemented in GSL shell in the next development cycle. You can choose between the following items and communicate your choice to the author by email:

development of a full featured, openGL based, 3D graphics module

develoment of a Graphical User Interface module to generate easily user interface to interact with plots by using GSL Shell/Lua functions

developement of a most versatile plot class that allows to create customized axes labels and legends.

development of a postscript backend to generate image in PostScript or EPS format

You can express in your choice also a feature that is not listed here.